Photographic shutter



(No Model.)

A. G. CLARK.

PHOTOGRAPHIO SHUTTER.

Pg tentgd May 4, 1886..

vyilnesses:

UNITED STATES PATENT OFFICE.

ALVAX G. CLARK, OF CAMBRIDGEPORT, MASSACHUSETTS.

PHOTOGRAPHIC SHUTTER.

iZfiPECIPICATION forming part of Letters Patent No. 341,130, dated May 4, 1886.

Serial No. 185,430, (No model.)

T0 at whom it may concern:

Be it known that I, ALVAN G. CLARK, of Cambridgeport, in the State of Massachusetts, have invented a new and useful Improvement in Photographic Shutters, of which the following is a specification.

My invention relates to shutters for use in instantaneous photography.

The object of my invention is to provide a photographic shutter, compact, convenient, and strong, which can be adjusted to various rates of speed, and can act with great rapidity with the minimum of jar to the camera.

My invention consists, first, in the use, for a photographic shutter, of a receptacle which by itself serves as a double exposure, as herein shown and described, in connection with side pieces serves as a permanent double diaphragm or stop having an opening at each of two opposite points, and of a rotating double cutoff, inclosed within said double diaphragm, having an opening at each of two opposite points correspondingto the openings of the inclosingdiaphragm, in order that the four openings may come in line, when the cut-oii is rotated, to expose the sensitive plate to the rays of light from the object photographed, and that the rays of light from the object photographed may be shut out by this double cut-off, whereby the exposure is made substantially twice as rapidly as an exposure made with a single cut oft having the same rate of speed; or, in other words, a rapid exposure to be made in a given time can be made in such time with this double diaphragm and double cut-off by the expenditure of substantially one-half the force required to make the exposure in the same time with a single diaphragm and single cutoff that is, a diaphragm and cutoff, each requiring and having but one opening-and the force exerted being less the jar to the camera is correspondingly less.

As herein shown and described, the shutter and operating-spring are placed within the lens-tube and connected with it, and the mechanism for controlling the same is placed without the lens-tube and connected with it. The shutter and its operating mechanism may be distinct from the lens-tube, and be made to fit upon or into the lens-tube when in use; and, as herein shown and described, the diaphragm and inclosed cut-oil are hollow cylinders, it is evident that the same result could be attained without departing from my invention by the use of asimilar permanent diaphragm inclosed within, instead of inclosing, a rotating cut-off, provided the passage of light around the inclosing cut-off be prevented; and it is further evident that the two openings of the inclosed cut-oii or the inclosed diaphragm, as the case may be, might be formed by means of an open ing passing through an otherwise solid inclosed cutoii? or diaphragm between points of the same corresponding to the positions of the two openings of the hollow inclosed cutoff or diaphragm without departing from my invention. It is further evident that the same result, to a modified degree, could be attained without departing from my invention, by the use 01' this double cut-off with asingle diaphragm that is, a diaphragm requiring and having but one opening-as shown in Figs. 7 and S.

In the drawings, Figure 1 is an inverted plan of my invention, the shutter placed within the lenstube and in position to be operated to take a picture, the diaphragm openings closed by the cut-off. Fig. 2 is a sectional elevation of Fig. 1 on the line 4v :0. Fig. 3 is a partial sectional plan of the lens-tube, shutter, and side pieces at positions of the same indicated by the line y 11 in Fig. 2. Fig. etis apartial view of Fig. 3, except that here the diapragm and cut-off openings are shown at the instant they are in line in making an exposure. Fig. 5 is the same as Fig. 4, except that here the diaphragm and cut-off openings are shown at the instant they open to admit the central rays of light. Fig. 6 is the same as Fig. 4-, except that here the diaphragm and eutofl' openings are shown at the instant they close to shut out the central rays of light. Fig. 7 is the same as Fig. 1-, except that here the diaphragiii-opening is shown as singlethat is, requiring and having but one opening. Fig. 8 is the same as Fig. 7, except that here the diaphragm-opening is shown closed by the cutoff.

The broken lines passing through Figs. 3,

4, 5, 6, 7, andS indicate the central lines of light from the object photographed.

The movable hook shown in broken lines in Fig. 1 to hold the lock K when it is desired to have the openings in line, as shown in Fi 4, for the purpose of focusing or for giving a time-exposure.

T is the lens-tube; F, the receptacle serving in connection with the side pieces, W, as the permanent diaphragm or stop; I, a threaded neck, within which the screw-cap Bis worked to regulate the spiral spring S. The spring S is attached to the cap B at S, and coiled around the shaft R, and attached to the plate P of the cutoff O at S The shaft R is free to rotate in the cap B, and is fixed to the plate P. The shaft R attached to the plate P of the cut-ofi', passes through the cap B, free to rotate therein, and is rigidly connected with the lock K. The lock K,when the shutter is in position to be operated, is held by the tension of the'spring S against the spring piston-rod catch 0. When the catch 0 is removed from contact with the lock- K, by means of air sent from an air-bulb through the rubber tube U, as shown in the drawings, or otherwise removed, the lock K being released, the spring S causes the cut-off O to rotate, and the openings D D of the cutoff to pass the openings E E of the receptacle F, as shown, and thereby open and close the diaphragm-openings, and admit the light from the object photographed to the sensitive plate and shut out the same, the lock Kflying around and being caught and held by the spring- 2. A photographic-camera shutter consist ing of an exposer provided with an aperture and a cylinder provided with apertures corresponding to the aperture of the exposer, and adapted to revolve, whereby by the continuous revolution of said cylinder the several apertures maybe brought into line and out of line, substantially as described, for the purpose specified.

I ALVAN G. CLARK. \Vitnesses:

' WALDRoN Buns,

HENRY MITCHELL. 

